841676 - Verify that Compositor task priority prevents it from being preempted unexpectedly by content tasks

Status: RESOLVED DUPLICATE of bug 982972

(Core :: General, defect)

Description

[Chris Jones [:cjones] inactive; ni?/f?/r? if you need me]

The intention (on b2g at least) is that the compositor thread runs with "master process" priority, higher than foreground content tasks.  (Nice 0 vs. 1.)

We have evidence that suggests the compositor is running with the same priority as foreground processes, which would be very bad indeed.  We may have fixed this in the meantime.

Comment 1

[Chris Jones [:cjones] inactive; ni?/f?/r? if you need me]

Checking against

$ (cd gecko/ && git rev-parse HEAD && cd ../gaia && git rev-parse HEAD)
b253a8ffb1070133f7d230fb7eedc504e0df1612
ee6b803fefdec4d0c0df5a2da454bcf2e09a2d3c

I see (the task nice value is field 19)

$ adb shell cat /proc/6249/stat | awk '{print $19}'
6249 (Compositor) S 1 6236 0 0 -1 4194624 137029 10791 1112 70 33301 21525 333 32 20 0 42 0 2014811 170512384 13335 4294967295 32768 125476 3200998272 1133509872 1074689772 0 0 4096 50927 4294967295 0 0 -1 0 0 0 0 0 0
$ adb shell cat /proc/6249/stat | awk '{print $19}'
0

and

$ adb shell cat /proc/6345/stat
6345 (Settings) S 6236 6236 0 0 -1 4194560 58705 0 713 0 12752 1656 0 0 21 1 11 0 2017401 81883136 5965 4294967295 32768 33944 3196590496 3196587368 1073992496 0 0 4096 34536 4294967295 0 0 17 0 0 0 0 0 0
$ adb shell cat /proc/6345/stat | awk '{print $19}'
1

This corresponds to priority values of 20 and 21.

Comment 2

[Justin Lebar (not reading bugmail)]

The compositor /process/?

How do I identify it, from within Gecko?